Printed circuit boards, integrated circuit wafers and electronic packages and other electronic components are widely used in almost every aspect of the electronics industry. It is important to be able to test the electrical integrity and performance characteristics of these components during manufacture and/or in the field. The ability to perform testing in a facile manner leads to decreased product development time, improved product quality control, and improved technical (diagnostic) service in the field.
The ability to adequately test various boards, wafers and packages in a fast, economical and reliable manner becomes more challenging with the ever increasing density of devices contained on these electronic components. Additional challenges may also be presented where the size (e.g., device-occupied surface area) of these electrical components is also increasing. In meeting these testing challenges, it is naturally desirable to minimize the capital outlay for new test equipment. It is highly desirable to adapt current testing equipment to the testing of more complex electronic components. The ability to adapt testing equipment can result in the ability to avoid or postpone capital investment in testing equipment while still meeting the testing objectives.
Most electronic testing equipment contains two primary functions, namely (1) an electronics section for performing testing protocols and/or reporting test results and (2) an interface between the testing equipment electronics and the electronic component or device under test (DUT). The electronics section of the test equipment used to perform the DUT testing is often fairly adaptable to the increased electrical testing complexity.
While the testing power of electronics section may be adequate or easily adaptable, the ability to efficiently interface the testing electronics with the actual DUT to be tested may present a challenge. The interface in most testing equipment involves the use of a test head. The test head typically engages the DUT. Contacts (pins) in the test head are brought into electrical contact with locations on the DUT. Thus, the test head typically contains a plurality of contacts as well as means for engaging the DUT and establishing physical contact (of sufficient electrical conductivity) between locations on the DUT and the test head contacts. The established electrical connections in turn can be used by the electronics section of the testing equipment to perform the desired testing.
The ability of the electronics section to perform testing efficiently may be held back by the number of contacts that the test head can simultaneously establish with the DUT. Thus, the ability to increase the number of contacts is often desirable from the point of improved testing efficiency. The desire to increase the number of simultaneous contacts generally increases with the complexity of the DUT to be tested. While more contact points are desired, the physical space occupied by the test head and DUT is often fixed by the physical configuration of the overall testing equipment.
The limitation on the physical space available for contact pins and the desire to house more contact pins in the test head leads to a desire to place contact pins in a more dense configuration. Increased pin density often leads to difficulty in the ability to replace worn out or defective contact pins on an economical and convenient basis. For example, if screws are used to fix the pins in place, those screws may have to be reduced in size to accommodate more pins. Smaller screws (or other fasteners) generally have increased incidence of mishandling leading to poorly fastened or unattached screws which may damage the test head or the device under test.
In addition to replaceability, increased pin density places challenges on the ability to maintain desired contact pin configurations in the test head as well as the appropriate/desired electrical environment for the pins. For example, where coaxial pogo pins are used, there is often a desire to commonly ground the sheath conductors for each pin while avoiding the grounding of the pins to other components of the test head.
Thus, there is a demand for contact pin holder designs which improve the usage of physical space occupied by the test head whereby more contacts can be simultaneously made in the same test head space while maintaining economical and convenient pin replaceability, precise pin alignment and appropriate electrical environment. These demands are especially apparent in the context of existing auto handler and manual DUT board testing equipment as well as in the area of wafer-level testing and bum-in using wafer prober apparatus which typically involves the interfacing of probe cards and wafers (or other device under test) with various contact structures.
The invention provides contact pin holder assemblies which enable the provision of more contact points in a test head space while maintaining economical and convenient pin replaceability, precise pin alignment and appropriate electrical environment. The invention enables these benefits by an improved contact pin holder assembly design which is generally characterized by an engagement structure at the periphery of a opening in a contact support housing which engagement structure releasably engages one or more modules containing one or more contact pins.
In one aspect, the invention encompasses a contact pin holder assembly for holding contact pins in an opening of a contact pin support housing, the assembly comprising:
(a) a first rail attached to the support housing about at least a portion of the opening, the first rail containing a rail coupling means for releasably engaging coupling means from one or more pin-containing modules,
(b) means for attaching the rail to the support housing,
(c) at least one contact pin-containing module, the module having a first module coupling means for releasably engaging the rail coupling means, whereby engagement of the rail coupling means and module coupling means causes the module to become releasably fixed in position relative to the contact pin support housing.
The assembly preferably comprises a plurality of rails fixed about the opening in the support housing. The rails preferably contain a plurality of coupling means whereby a plurality of pin-containing modules can be releasably secured to the rail. Preferably, each module is releasably secured through at least two rail coupling means, more preferably couplings on separate rails which face each other in a substantially parallel relationship. The coupling means of the rail and/or module preferably include at least one spring element which can be reversibly deflected.
The invention further encompasses testing apparatus and methods using the contact pin assembly of the invention. The invention is especially useful in the context of manual test, auto handler and wafer prober testing equipment.
These and other aspects of the invention are described in further detail below.